What statement accurately reflects the issue with personal testimonials from a critical thinking perspective?

Personal testimonials are scientifically unreliable due to the lack of control for errors and bias in their collection processes.

Personal testimonials are easy to process, making them reliable sources of information.

Many people are eager to put forth cognitive effort when evaluating personal testimonials.

There is a foolproof way to prove causation between a specific action and a desired outcome using personal testimonials.